linux - 有没有办法获取unix套接字连接另一端的uid

Question

有没有办法让 UNIX 域套接字监听器只接受来自特定用户的连接(chmod/chown 不适用于抽象套接字 afaik)，或者在另一个word，获取传入连接的 uid(在 Linux 上)？

在 Linux 上使用抽象 unix 套接字的 Dbus 有一个函数 GetConnectionUnixUser，polkit 使用它来确定调用者。所以我想 dbus-daemon 一定有办法做到这一点。有谁知道它是如何工作的？

Answer 1

检查对等凭据的最简单方法是使用 SO_PEERCRED .对套接字 sock 执行此操作:

int len;
struct ucred ucred;

len = sizeof(struct ucred);
if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &ucred, &len) == -1)
    // check errno

printf("Credentials from SO_PEERCRED: pid=%ld, euid=%ld, egid=%ld\n",
        (long) ucred.pid, (long) ucred.uid, (long) ucred.gid);

SO_PEERCRED
          Return the credentials of the foreign process connected to
          this socket.  This is possible only for connected AF_UNIX
          stream sockets and AF_UNIX stream and datagram socket pairs
          created using socketpair(2); see unix(7).  The returned
          credentials are those that were in effect at the time of the
          call to connect(2) or socketpair(2).  The argument is a ucred
          structure; define the _GNU_SOURCE feature test macro to obtain
          the definition of that structure from <sys/socket.h>.  This
          socket option is read-only.

来自tlpi example . PostgreSQL有一些其他 unice 的变体。